Polymer cutting block including metallic protective bushings and method of using same

ABSTRACT

An orthopaedic surgical instrument includes a polymer cutting block having a number of metallic cutting guides secured thereto. A pair of metallic bushings function as saw stops at the medial and lateral ends of the cutting slot during an orthopaedic surgical procedure.

This application claims priority under 35 U.S.C. § 120 to U.S. Utilitypatent application Ser. No. 16/147,620, now U.S. Pat. No. 10,828,047,which claims priority to U.S. Utility patent application Ser. No.13/785,287, now U.S. Pat. No. 10,111,673; the entirety of both of whichis expressly incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to orthopaedic surgicalinstruments and, more particularly, to surgical instruments used toresect a patient's bone.

BACKGROUND

Joint arthroplasty is a well-known surgical procedure by which adiseased and/or damaged natural joint is replaced by a prosthetic joint.Typical artificial joints include knee prostheses, hip prostheses,shoulder prostheses, ankle prostheses, and wrist prostheses, amongothers. To facilitate the replacement of the natural joint with theprosthesis, orthopaedic surgeons use a variety of orthopaedic surgicalinstruments such as, for example, saws, drills, reamers, rasps,broaches, cutting blocks, drill guides, milling guides, and othersurgical instruments.

SUMMARY

According to one aspect of the disclosure, an orthopaedic surgicalinstrument includes a polymer 4-in-1 femoral cutting block having achamfer cutting slot defined therein. A first metallic planar cuttingguide is secured within the chamfer cutting slot of the polymer 4-in-1femoral cutting block. A second metallic planar cutting guide is alsosecured within the chamfer cutting slot of the polymer 4-in-1 femoralcutting block. The second metallic planar cutting guide is arranged atan oblique angle relative to, and spaced apart from, the first metallicplanar cutting guide. A first metallic bushing is secured within thechamfer cutting slot of the polymer 4-in-1 femoral cutting block, withan outer surface of the first metallic bushing being positioned at alateral end of each of the first and second metallic planar cuttingguides. A second metallic bushing is also secured within the chamfercutting slot of the polymer 4-in-1 femoral cutting block, with the outersurface of the second metallic bushing being positioned at a medial endof each of the first and second metallic planar cutting guides.

The outer surface of the first metallic bushing may be spaced apartlaterally from the lateral end of each of the first and second metallicplanar cutting guides, or may be positioned in contact with the lateralend of each of the first and second metallic planar cutting guides.Likewise, the outer surface of the second metallic bushing may be spacedapart medially from the medial end of each of the first and secondmetallic planar cutting guides, or positioned in contact with the medialend of each of the first and second metallic planar cutting guides.

Each of the first and second metallic bushings may be embodied ascylindrically-shaped bushings having an elongated bore extendingtherethrough.

In an embodiment, the second metallic planar cutting guide is spacedapart from the first metallic planar cutting guide in theanterior/posterior direction.

The orthopaedic surgical instrument may also include a third metallicplanar cutting guide secured within the chamfer cutting slot of thepolymer 4-in-1 femoral cutting block, and a fourth metallic planarcutting guide secured within the chamfer cutting slot of the polymer4-in-1 femoral cutting block. The fourth metallic planar cutting guidemay be arranged at an oblique angle relative to the third metallicplanar cutting guide.

The polymer 4-in-1 femoral cutting block may also have an anteriorcutting slot defined therein. The anterior cutting slot is spaced apartanteriorly from the chamfer cutting slot, and has a metallic anteriorcutting guide secured within it.

Moreover, the polymer 4-in-1 femoral cutting block may also have aposterior cut surface defined therein. The posterior cut surface isspaced apart posteriorly from the chamfer cutting slot, and has ametallic posterior cutting guide secured to it.

According to another aspect, an orthopaedic surgical instrument includesa polymer 4-in-1 femoral cutting block having a chamfer cutting slotdefined therein, and a metallic captured chamfer cutting guide assemblysecured within the chamfer cutting slot. The metallic captured chamfercutting guide assembly includes a first metallic planar cutting guideand a second metallic planar cutting guide arranged at an oblique anglerelative to, and spaced apart from, the first metallic planar cuttingguide. The metallic captured chamfer cutting guide assembly alsoincludes a first metallic bushing having its outer surface positioned ata lateral end of each of the first and second metallic planar cuttingguides, and a second metallic bushing having its outer surfacepositioned at a medial end of each of the first and second metallicplanar cutting guides.

The outer surface of the first metallic bushing may be spaced apartlaterally from the lateral end of each of the first and second metallicplanar cutting guides, or may be positioned in contact with the lateralend of each of the first and second metallic planar cutting guides.Likewise, the outer surface of the second metallic bushing may be spacedapart medially from the medial end of each of the first and secondmetallic planar cutting guides, or positioned in contact with the medialend of each of the first and second metallic planar cutting guides.

Each of the first and second metallic bushings may be embodied ascylindrically-shaped bushings having an elongated bore extendingtherethrough.

In an embodiment, the second metallic planar cutting guide is spacedapart from the first metallic planar cutting guide in theanterior/posterior direction.

The orthopaedic surgical instrument may also include a third metallicplanar cutting guide secured within the chamfer cutting slot of thepolymer 4-in-1 femoral cutting block, and a fourth metallic planarcutting guide secured within the chamfer cutting slot of the polymer4-in-1 femoral cutting block. The fourth metallic planar cutting guidemay be arranged at an oblique angle relative to the third metallicplanar cutting guide.

The polymer 4-in-1 femoral cutting block may also have an anteriorcutting slot defined therein. The anterior cutting slot is spaced apartanteriorly from the chamfer cutting slot, and has a metallic anteriorcutting guide secured within it.

Moreover, the polymer 4-in-1 femoral cutting block may also have aposterior cut surface defined therein. The posterior cut surface isspaced apart posteriorly from the chamfer cutting slot, and has ametallic posterior cutting guide secured to it.

According to another aspect, an orthopaedic surgical instrument includesa polymer cutting block having a cutting slot defined therein, and ametallic captured cutting guide assembly secured within the cuttingslot. The captured metallic chamfer cutting guide assembly may include afirst metallic planar cutting guide, and a second metallic planarcutting guide spaced apart from the first metallic planar cutting guide.The captured metallic chamfer cutting guide assembly may also include afirst metallic bushing having an outer surface thereof positioned at afirst end of each of the first and second metallic planar cuttingguides, and a second metallic bushing having an outer surface thereofpositioned at a second end of each of the first and second metallicplanar cutting guides.

Each of the first and second metallic bushings may be embodied ascylindrically-shaped bushings having an elongated bore extendingtherethrough.

In an embodiment, the second metallic planar cutting guide is spacedapart from the first metallic planar cutting guide in theanterior/posterior direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is a perspective view of an orthopaedic surgical instrument;

FIG. 2 is an elevation view showing the outer surface of the orthopaedicsurgical instrument of FIG. 1;

FIG. 3 is an elevation view of the bone-engaging surface of theorthopaedic surgical instrument of FIG. 1;

FIG. 4 is a cross section view of the orthopaedic surgical instrument,taken along the line 4-4 of FIG. 2, as viewed in the direction of thearrows;

FIG. 5 is a perspective view showing a pair of fixation pins secured toa distal end of a patient's femur;

FIG. 6 is a view similar to FIG. 5, but showing the orthopaedic surgicalinstrument of FIG. 1 being used to perform the anterior and posteriorcuts on the distal end of the patient's femur; and

FIG. 7 is a view similar to FIG. 6, but showing the orthopaedic surgicalinstrument of FIG. 1 being used to perform the chamfer cuts on thedistal end of the patient's femur.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior,medial, lateral, superior, inferior, etcetera, may be used throughoutthe specification in reference to the orthopaedic implants and surgicalinstruments described herein as well as in reference to the patient'snatural anatomy. Such terms have well-understood meanings in both thestudy of anatomy and the field of orthopaedics. Use of such anatomicalreference terms in the written description and claims is intended to beconsistent with their well-understood meanings unless noted otherwise.

Referring to FIGS. 1-4, one embodiment of a single use orthopaedicsurgical instrument 10 is shown. As its name implies, the single useorthopaedic surgical instrument 10 is intended to be disposed of afteruse in a single orthopaedic procedure. In the illustrative embodimentdescribed herein, the orthopaedic surgical instrument is embodied as asingle use 4-in-1 cutting block 12 for use in the surgical preparationof the patient's distal femur during a knee replacement procedure. Aswill be discussed below in greater detail, a 4-in-1 cutting block 12 isused to perform four cuts on the patient's distal femur with the sameblock—an anterior cut, a posterior cut, and two chamfer cuts.

As a single use instrument, the 4-in-1 cutting block 12 may be formedfrom polymeric materials such as, for example, polyamide,polyphenylsulfone, or polyketone. In such an embodiment, the surfacesused to guide surgical instruments, such as cutting guide surfaces forguiding bone saws and bushings for guiding drills and surgical pins, areformed from a metallic material such as, for example, steel, titaniumalloy, or cobalt chromium alloy. Such use of metallic components or“inserts” prevents the surgical tools from coming into contact with thepolymeric materials of the block's body.

The metallic components described herein may be secured to the polymer4-in-1 cutting block in a number of different manners. For example, themetallic components may be overmolded to the polymer cutting block orotherwise secured to it as part of the molding process of the block. Themetallic components may also be welded to the cutting block or securedto it with an adhesive. Other methods of securing the metalliccomponents may also be employed.

The 4-in-1 cutting block 12 includes an outer surface 20 and abone-engaging surface 22 positioned opposite the outer surface 20. The4-in-1 cutting block 12 has an anterior cutting slot 24 formed near itsanterior end 26. The anterior cutting slot 24 is an elongated slotextending in the medial/lateral direction. The anterior cutting slot 24extends through the entire thickness of the 4-in-1 cutting block 12—thatis, the anterior cutting slot 24 extends from the cutting block's outersurface 20 to its bone-engaging surface 22 thereby being open to bothsurfaces. A metallic anterior cutting guide 28 is secured within theanterior cutting slot 24 of the polymer 4-in-1 cutting block 12. Theanterior cutting guide 28 lines the anterior cutting slot 24 and isembodied as a captured cutting guide (i.e., it is closed on all sides soas to capture a saw blade therein), although the cutting block 12 andthe cutting guide 28 may alternatively be embodied as a non-capturedcutting guide. The anterior cutting guide 28 is sized and shaped toreceive the blade (see FIG. 6) of a surgical saw or other cuttinginstrument and orient the blade to resect the anterior surface of thepatient's femur during an orthopaedic surgical procedure.

The 4-in-1 cutting block 12 has a posterior cutting surface 30 formednear its posterior end 32. The posterior cutting surface 30 is anelongated surface extending in the medial/lateral direction. Theposterior cutting surface 30 extends the entire thickness of the 4-in-1cutting block 12—that is, it extends from the cutting block's outersurface 20 to its bone-engaging surface 22. A metallic posterior cuttingguide 34 is secured to the posterior cutting surface 30 of the polymer4-in-1 cutting block 12. The posterior cutting guide 34 is sized andshaped to support and guide the blade (see FIG. 6) of a surgical saw orother cutting instrument and orient the blade to resect the posteriorsurface of the patient's femur during an orthopaedic surgical procedure.In the illustrative embodiment described herein, the posterior cuttingguide 34 is embodied as a non-captured cutting guide, although it mayalternatively be embodied as a captured cutting guide.

The 4-in-1 cutting block 12 has an chamfer cutting slot 36 formed nearits middle. Specifically, the chamfer cutting slot 36 is locatedposteriorly of the anterior cutting slot 24 and anteriorly of theposterior cutting surface 30. The chamfer cutting slot 36 is anelongated slot extending in the medial/lateral direction. The chamfercutting slot 36 extends through the entire thickness of the 4-in-1cutting block 12—that is, it extends from the cutting block's outersurface 20 to its bone-engaging surface 22 and, as a result, opens toboth surfaces. The chamfer cutting slot 36 is defined by a sidewall 38of the 4-in-1 cutting block that includes an anterior edge 40 extendingin the medial/lateral direction and a posterior edge 42 that is spacedapart from the anterior edge 40 and likewise extends in themedial/lateral direction. The chamfer cutting slot 36 has enlargedrounded medial and lateral ends. In particular the medial edge 44 of thesidewall 38 defining the chamfer cutting slot 36 is cylindrical in shape(i.e., circular when viewed in the front elevation of FIG. 2) and has adiameter that is larger than the A/P width of the slot 36 (i.e., thedistance between anterior edge 40 and the posterior edge 42 of thesidewall 38). On the opposite end of the chamfer cutting slot 36, thelateral edge 46 of the sidewall 38 is identical in shape and size. Inessence, in the illustrative embodiment described herein, the chambercutting slot 36 takes on the form of two cylinders spaced at oppositemedial and lateral ends connected by a elongated planar slot.

As can be seen in FIGS. 1, 2, and 4, a metallic captured chamfer cuttingguide assembly 50 is positioned in the chamfer cutting slot 36. Thechamfer cutting guide assembly 50 includes a metallic planar cuttingguide 52 secured to the anterior edge 40 of the sidewall 38 defining theanterior side of the chamfer cutting slot 36, along with a metallicplanar cutting guide 54 secured to the posterior edge 42 of the sidewall38 defining the posterior side of the chamfer cutting slot 36. As can beseen best in FIG. 4, the planar cutting guides 52, 54 are spaced apartfrom one another in the anterior/posterior direction and are arranged atan oblique angle relative to one another. The longitudinal axis of theplanar cutting guides 52, 54 extends in the medial/lateral direction.

The medial and lateral ends of the captured chamfer cutting guideassembly 50 are defined by a pair of metallic bushings 56, 58. Inparticular, the metallic bushing 56 is positioned in the enlargedcylindrically-shaped medial end of the chamfer cutting slot 36—that is,the metallic bushing 56 is secured in contact with the medial edge 44 ofthe sidewall 38 defining the medial end of the chamfer cutting slot 36.The metallic bushing 58 is positioned in the enlargedcylindrically-shaped lateral end of the chamfer cutting slot 36—that is,the metallic bushing 58 is secured in contact with the lateral edge 46of the sidewall 38 defining the lateral end of the chamfer cutting slot36.

The metallic bushings 56, 58 are cylindrically-shaped and have anelongated bore 60 extending therethrough. The elongated bore 60 is sizedto receive a fixation or guide pin for pinning the 4-in-1 cutting blockto the patient's distal femur (see FIG. 7), and, optionally, a drillsuch that the patient's femur may be pre-drilled prior to installationof the guide pins if the surgeon so desires. The metallic bushings 56,58 are identical in shape and include an annularly-shaped outer surface62. As can be seen in FIG. 2, the outer surface 62 of the metallicbushing 56 is positioned at the medial end 64 of the planar cuttingguides 52, 54, with the outer surface 62 of the metallic busing 58 beingpositioned at the lateral end 66 of the planar cutting guides 52, 54. Inthe illustrative embodiment described herein, the outer surface 62 ofthe metallic bushings 56, 58 is slightly spaced apart from therespective medial end 64 and lateral end 66 of the planar cutting guides52, 54 (i.e., the bushings 56, 58 are not positioned in contact with theplanar cutting guides 52, 54). Such spacing allows for capture of theblade of a bone saw, while also providing for relief from overly tighttolerances in the manufacturing process. However, in anotherillustrative embodiment, the metallic bushings 56, 58 are positioned incontact with the respective medial end 64 and lateral end 66 of theplanar cutting guides 52, 54.

As can be seen best in FIGS. 1 and 4, the 4-in-1 cutting block 12 has awedge component 70 secured to its bone-engaging surface 22. Like the4-in-1 cutting block 12, the wedge component 70 is formed from polymericmaterials. The wedge component 70 has a wedge-shaped cutting surface 72.The “leading” edge 74 of the wedge-shaped cutting surface 72 extendsinto the chamfer cutting slot 36. A metallic planar cutting guide 76 issecured to the anterior surface 78 of the wedge-shaped cutting surface72, with a metallic planar cutting guide 80 being secured to theposterior surface 82 of the wedge-shaped cutting surface 72. Like thecutting guides 52, 54, the planar cutting guides 76, 80 are spaced apartfrom one another and are arranged at an oblique angle relative to oneanother. The longitudinal axis of the planar cutting guides 76, 80extends in the medial/lateral direction. As can be seen in FIG. 4, thecutting guide 76 is spaced apart from, and parallel to, the cuttingguide 52, with the cutting guide 80 being spaced apart from, andparallel to, the cutting guide 54. In such a way, the cutting guides 52,76 cooperate to guide a saw blade during performance of the anteriorchamfer cut, with the cutting guides 54, 80 cooperating to guide the sawblade during performance of the posterior chamfer cut (see FIG. 7).

Like the planar cutting guides 52, 54, the outer surface 62 of themetallic bushing 56 is positioned at the medial end of the planarcutting guides 76, 80, with the outer surface 62 of the metallic busing58 being positioned at the lateral end of the planar cutting guides 76,80. In the illustrative embodiment described herein, the outer surface62 of the metallic bushings 56, 58 is slightly spaced apart from therespective medial end and lateral end of the planar cutting guides 76,80 (i.e., the bushings 56, 58 are not positioned in contact with theplanar cutting guides 76, 80). Such spacing allows for capture of theblade of a bone saw, while also providing for relief from overly tighttolerances in the manufacturing process. However, in anotherillustrative embodiment, the metallic bushings 56, 58 are positioned incontact with the respective medial end and lateral end of the planarcutting guides 76, 80.

The 4-in-1 cutting block 12 has a plurality of guide holes 86 definedtherein that are sized to receive a pair of fixation or guide pins 88(see FIG. 6). The holes 86 are positioned between the anterior cuttingslot 24 and the chamfer cutting slot 36 and extend between the outersurface 20 and the bone-engaging surface 22 of the cutting block 12. Theholes 86 are arranged in a staggered pattern to permit the surgeon tochange the position of the cutting block 12 on the patient's femurwithout having to remove the fixation pins 88, as described in greaterdetail below.

The 4-in-1 cutting block 12 also includes another plurality of guideholes 90 positioned between the chamfer cutting 36 and the posteriorcutting surface 30. Each guide hole 90 is sized to receive one of thefixation pins 88 in a similar manner to the guide holes 86 and therebyextends between the outer surface 20 and the bone-engaging surface 22 ofthe cutting block 12. Like the guide holes 86, the guide holes 90 arearranged in a staggered pattern to permit the surgeon to change theposition of the cutting block 12 on the patient's femur without havingto remove the fixation pins 88.

In operation, the surgeon may utilize the orthopaedic surgicalinstrument 10 to prepare the distal end 18 of the patient's femur 20 toreceive a prosthetic femoral component. To do so, the surgeon may securethe 4-in-1 cutting block 12 to the patient's femur 20 and thereafter usethe metallic cutting guides of the cutting block 12 to guide a cuttingsaw blade in making a series of four resections of the distal end 18 ofthe patient's femur 20.

During an orthopaedic surgical procedure, the surgeon may first resectthe distal end 18 of the patient's femur 20 to create asurgically-prepared distal surface 92. The surgeon may then secure apair of fixation pins 88 to the surgically-prepared distal surface 92 ofthe patient's femur 20, as shown in FIG. 5. To do so, the surgeon maysize the patient's femur 20 for the prosthetic femoral component and setthe femoral rotation. One exemplary procedure for locating fixation pinsduring a femoral sizing and rotation setting procedure is described inthe SIGMA® Fixed Reference Surgical Technique by DePuy Orthopaedics,Inc. (2010), which is expressly incorporated herein by reference. Aftersizing the femoral component and setting the rotation, the surgeon mayattach the fixation pins 88 to the surgically-prepared distal surface 92of the patient's femur 20.

After attaching the fixation pins 88, the surgeon may position the4-in-1 cutting block 12 on the surgically-prepared distal surface 92 ofthe patient's femur 20. To do so, the surgeon may align the shafts 94 ofthe fixation pins 88 with a pair of the guide holes 86 of the 4-in-1cutting block 12. The surgeon may then advance the 4-in-1 cutting block12 over the shafts 94 in a direction toward the surgically-prepareddistal surface 92 of the patient's femur 20. The bone-engaging surface22 of the 4-in-1 cutting block 12 contacts the surgically-prepareddistal surface 92 when the instrument 10 is positioned on the distal end18 of the patient's femur 20, as shown in FIG. 6. If the surgeon desiresto relocate the 4-in-1 cutting block 12, the surgeon may utilize anothercombination of guide holes 86 to change the position of the cuttingblock 12 on the patient's femur 20. If additional fixation is necessary,the surgeon may insert additional fixation pins 88 through the guideholes 90 defined in the 4-in-1 cutting block 12.

Once installed in such a manner, the surgeon may use the 4-in-1 cuttingblock 12 to make a number of resections of the distal end 18 of thepatient's femur 20. For example, as shown in FIG. 6, the anteriorcutting guide 28 defines a resection plane that extends through thedistal end 18 of the patient's femur 20. The surgeon may advance acutting tool, such as, for example, a surgical cutting saw 96 throughthe anterior cutting guide 28 to engage the patient's femur 20 andoperate the surgical saw 96 to surgically prepare an anterior surface ofthe patient's femur 20 to receive the prosthetic femoral component. Thesurgeon may similarly use the posterior cutting guide 34 to resect theposterior condyles 98 of the patient's femur 20 and surgically preparethe posterior surfaces of the patient's femur 20 to receive theprosthetic femoral component.

As shown in FIG. 7, the surgeon may also use the captured chamfercutting guide assembly 50 in cooperation with the planar cutting guides76, 80 of the wedge component 70 to make chamfer cuts on the patient'sfemur 20. To do so, the surgeon may first insert fixation pins 88through the elongated bores 60 of the metallic bushings 56, 58 of thechamfer cutting guides assembly 50. The surgeon may then remove anyfixation pins 88 from the guide holes 86, 90 since fixation pins 88positioned in the guide holes 86, 90 would disrupt the chamfer cuttingprocess. The surgeon may then advance the surgical cutting saw 96through opening between the cutting guides 52, 76 to guide the saw 96during performance of the anterior chamfer cut (as shown in solid linesin FIG. 7), and thereafter through the opening between the cuttingguides 54, 80 to guide the saw 96 during performance of the posteriorchamfer cut (as shown in phantom lines in FIG. 7).

During performance of such chamfer cuts, the metallic cutting guides 52,54 function as a saw stop to prevent the saw 96 from engaging thepolymeric body of the 4-in-1 cutting block 12 that defines the anteriorand posterior edges of the chamfer cutting slot 36. Similarly, the outersurfaces 62 of the metallic bushings 56, 58 function as a saw stop toprevent the saw from engaging the polymeric body of the of the 4-in-1cutting block 12 that defines the medial and lateral edges of thechamfer cutting slot 36. Likewise, the wedge component's metalliccutting guides 76, 80 function as a saw stop to prevent the saw 96 fromengaging the wedge-shaped cutting surface 72 of the wedge component 12.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

For example, although use of the metallic bushings 56, 58 as saw stopshas herein been described in the illustrative example of a 4-in-1 block,it should be appreciated that other orthopaedic instruments may also beembodied with such a concept. For example, other orthopaedic cuttingblocks may be so embodied.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

1. An orthopaedic surgical instrument comprising: a polymer 4-in-1femoral cutting block having a chamfer cutting slot defined therein, afirst metallic planar cutting guide secured within the chamfer cuttingslot of the polymer 4-in-1 femoral cutting block, a second metallicplanar cutting guide secured within the chamfer cutting slot of thepolymer 4-in-1 femoral cutting block, the second metallic planar cuttingguide being arranged at an oblique angle relative to, and spaced apartfrom, the first metallic planar cutting guide, a first metallic bushingsecured within the chamfer cutting slot of the polymer 4-in-1 femoralcutting block, an outer surface of the first metallic bushing beingpositioned at a lateral end of each of the first and second metallicplanar cutting guides, and a second metallic bushing secured within thechamfer cutting slot of the polymer 4-in-1 femoral cutting block, anouter surface of the second metallic bushing being positioned at amedial end of each of the first and second metallic planar cuttingguides.